1. Field of the Invention
The invention relates to super-conductors and somewhat more particularly to stabilized super-conductors having a super-conductive region separated from a normally conductive region by a diffusion-inhibiting layer and a method of producing such stabilized super conductors.
2. Prior Art
Super-conductors having a super-conductive material composed of an intermetallic compound containing at least two elements, and, for stabilization, having a material which is normally conductive at operative temperatures of the super conductive material, with a diffusion-inhibiting material, such as tantalum, positioned between the cross-sectional regions of the normally-conductive and super-conductive materials are known. Such super-conductor structures are produced by first assembling the requisite components in proper order into a structural cross-section and subsequently deforming the so-assembled components one or more times, with intermediate annealing, so as to attain a cross-sectional reduction sufficient to obtain a desired structural cross-section.
Further details for a process of producing super-conductors of this type by this method are described in German Offenlegungsschrift No. 28 26 810. This prior art reference suggests that in manufacturing a stablized super-conductor, one can arrange a diffusion-inhibiting layer between the super-conductive regions and the regions which are normally conductive at operative temperatures of the super-conductive material. This diffusion-inhibiting layer typically is composed of tantalum for preventing tin (a typical element of the intermetallic compound forming the super-conductive material) from diffusing out of the region containing the super-conductive material into the copper (a typically normally conductive material), functioning to stabilize the super-conductor and thus from being able to reduce the conductivity of the copper region.
As a diffusion-inhibiting material, niobium, because it is more economical, can be utilized in place of tantalum. However, in such instance, tin (a typical element of the intermetallic compound forming the super-conductive material) would combine with the niobium diffusion-inhibiting layer to form a super-conductive Nb.sub.3 Sn layer, which in operation leads to "large area" super-conductive currents. This has, as a consequence, shielding effects, field variations during the self-excitation of magnets associated with the super-conductor as well as problems in current passage.